This invention relates to medical devices for injecting living bodies and, more particularly, to safety features incorporated therewith. In particular, it is directed to the springs and locking collars that can be used to releasably lock and automatically re-lock a retractable sleeve protecting the needle of a medical device.
In U.S. Pat. No. 4,998,922 by Thomas C. Kuracina entitled SAFETY SYRINGE CAP MINIMIZING NEEDLE-STICK PROBABILITY which issued 12 March 1991, a safety device for hypodermic needles and the like is shown. The inventions shown hereinafter are improvements thereto by inventors including and/or working with Mr. Kuracina. In the interest of simplicity herein, the teachings of that patent are incorporated herein by reference and the discussion of the background art will be kept to a minimum.
A typical prior art hypodermic syringe includes a barrel having a moving plunger therein. A needle having a sharp beveled tip extends from the end opposite the end of the barrel into which the plunger is inserted. The needle is covered by a removeable cap for safety purposes. The problem to be solved and avoided is the accidental sticking of users of the syringe by the tip after use where the tip may carry body fluids containing agents of hepatitis B, AIDS, and the like. Accidental needle stick is a very common problem in the health care industry and besides the risk of serious illness or even death as a result thereof, the insurance industry spends over a billion dollars a year in the testing of individuals who have been subjected to post-use needle stick.
The 1979 patent of Alvarez proposed a retractable plastic protective sleeve over the needle. The Alvarez sleeve has an inner hub which fits around the base of the needle and an outer hub through which the tip of the needle passes. The inner and outer hubs are connected by curved slats. When the needle is to be inserted into the body of a patient, the force required to move the sleeve from its extended position to its retracted position can be depicted as a straight line beginning with very little required force to initiate movement. Thus, there is really no actually safety from a large variety of ways in which accidental needle stick takes place. Even if the sleeve fully extends after use, a slight blow against a user or observer in the area will cause the sleeve to retract and the tip to stick the unfortunate person.
With respect to the action of the basic protective sleeve of the above-referenced Kuracina patent by comparison, a high degree of force is required to move the protective sleeve from its extended position covering the tip. Moreover, a spring-biased locking collar is added over the protective sleeve which all but prevents the protective sleeve from moving from its extended position covering the tip. The collar must be moved from its locked position to a retracted, unlocked position before the unique deformation qualities of the sleeve take effect. After use, the locking collar springs back to its locked position. Thus, in virtually all "accidental" contact with the tip end of a hypodermic syringe, actual penetration by the tip should be prevented.
In a co-pending application entitled MEDICAL INJECTION DEVICES WITH SAFETY FEATURES filed on even date herewith, certain improvements to the Kuracina protective sleeve are disclosed. The inventions described hereinafter are improvements to the spring and locking collar intended to make the Kuracina protective sleeve even safer and more easy to use while also adapting it to various mounting configurations.
Other objects and benefits of the inventions disclosed herein will become apparent from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.